690.9(C) Informational Note - Overcurrent protection

akloudless
akloudless Registered Users Posts: 2 ✭
in PV Installers Forum - NEC, Wiring, Installation #1

Looking for clarification from the experts. Q: Is the NEC 2017 code stating that the DC OCPD requirements are now the same for an unground and grounded inverter system?

Scenario:

Module max fuse series rating = 15a

16 strings(Paralleling 2 strings) - 8 string combiner input - Single input mppt ungrounded inverter.

My approach to this in the past would have been, + & - 15a fused Y connectors to a + and - 30a fuse for each string in the combiner.

Is it now code to install while eliminating fusing on either the + or - side of the DC circuits?

Thoughts?

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Comments

  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #2
    On certain grid tie inverters that are transformerless such as the Sunny Boy TL series you must have breakers on both the positive and negative p.v. wires as they are not referenced to ground. I do not know of any requirements for grounded systems to have breakers on both positive and negative wires. 
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